Bottom Line:
We have, therefore, established a new method for estimating the RBE of all BNCT dose components on the basis of the microdosimetric kinetic model.This method employs the probability density of lineal energy, y, in a subcellular structure as the index for expressing RBE, which can be calculated using the microdosimetric function implemented in the particle transport simulation code (PHITS).The accuracy of this method was tested by comparing the calculated RBE values with corresponding measured data in a water phantom irradiated with an epithermal neutron beam.

RRU109F5: Measured α value for each of the four major BNCT dose components as a function of calculated y*. The solid line and open markers denote the relationship between α and y* expected from Eq. (3).

Mentions:
Figure 5 shows measured α values for the boron, neutron and gamma doses as a function of calculated y*. The relationship between α and y* resulting from Eq. (3) is also revealed in this figure. It is evident from the graph that the calculated α value of the boron and proton doses agrees with the corresponding measured data very well. The agreement for proton dose demonstrates that the α parameters for the nitrogen and hydrogen doses can be estimated from calculated y*, and their α values are estimated to be 1.21 Gy−1 and 0.91 Gy−1, respectively.Fig. 5.

RRU109F5: Measured α value for each of the four major BNCT dose components as a function of calculated y*. The solid line and open markers denote the relationship between α and y* expected from Eq. (3).

Mentions:
Figure 5 shows measured α values for the boron, neutron and gamma doses as a function of calculated y*. The relationship between α and y* resulting from Eq. (3) is also revealed in this figure. It is evident from the graph that the calculated α value of the boron and proton doses agrees with the corresponding measured data very well. The agreement for proton dose demonstrates that the α parameters for the nitrogen and hydrogen doses can be estimated from calculated y*, and their α values are estimated to be 1.21 Gy−1 and 0.91 Gy−1, respectively.Fig. 5.

Bottom Line:
We have, therefore, established a new method for estimating the RBE of all BNCT dose components on the basis of the microdosimetric kinetic model.This method employs the probability density of lineal energy, y, in a subcellular structure as the index for expressing RBE, which can be calculated using the microdosimetric function implemented in the particle transport simulation code (PHITS).The accuracy of this method was tested by comparing the calculated RBE values with corresponding measured data in a water phantom irradiated with an epithermal neutron beam.